Part D vs. Medicare Advantage: What's the Difference?
Our state pages show two different tables — standalone Part D plans and Medicare Advantage plans by county — and the categories can blur together if you're new to Medicare. They're structurally different products with different tradeoffs. Here's the distinction that actually matters when you're choosing.
Start with what Original Medicare covers
Original Medicare is Part A (hospital care) and Part B (doctor visits, outpatient care) — run directly by the federal government. Neither one covers prescription drugs. That gap is exactly what Part D and Medicare Advantage each fill, in different ways.
Path 1: Original Medicare + standalone Part D (PDP)
You keep Original Medicare exactly as-is — any doctor or hospital that accepts Medicare, no network restrictions — and add a standalone Prescription Drug Plan (PDP) from a private insurer just to cover medications. PDPs are typically priced and sold statewide (that's why our state pages show one PDP table per state, not per county). Many people pair this with a Medigap supplemental policy to cover Original Medicare's out-of-pocket gaps.
Path 2: Medicare Advantage (Part C)
Instead of Original Medicare, you enroll in a private plan that's required to cover at least everything Original Medicare covers, and usually bundles in more: dental, vision, hearing, and often prescription drugs built into the same plan. A Medicare Advantage plan that includes drug coverage is called MA-PD; one that doesn't is MA-only (uncommon — mostly for people who get drug coverage elsewhere, like a union or VA plan). The tradeoff for the extra benefits is a network: most MA plans are HMOs or PPOs with a defined list of doctors and hospitals, unlike Original Medicare's "any provider that accepts Medicare" model. MA plan availability and pricing is set at the county level, which is why our county pages exist — the exact same plan name can have different premiums, or not be offered at all, one county over.
Where SNPs fit in
Special Needs Plans (SNPs) are a category of Medicare Advantage plan restricted to a specific group: dual-eligible for Medicare and Medicaid, a specific chronic condition, or residents of a long-term care institution. They're tailored (and often at $0 premium) for people who qualify, but you can't enroll unless you meet the specific criteria.
The one rule that trips people up
You cannot be enrolled in both a standalone Part D plan and an MA-PD plan at the same time — enrolling in one typically triggers automatic disenrollment from the other, since together they'd be duplicate drug coverage. If you're on Original Medicare with a standalone PDP and you switch to an MA-PD plan, your PDP enrollment ends automatically, and vice versa.
How to actually decide
- Value network freedom and already have a Medigap policy? Original Medicare + standalone Part D is the classic pairing.
- Want dental/vision/hearing bundled in, and don't mind a network? MA-PD is usually the lower out-of-pocket-cost path, especially at $0 premium.
- Either way, check your specific drugs. Every plan — Part D or MA-PD — has its own formulary, so the "best" plan on paper can still be the wrong one if it doesn't cover your medications well.